1, 首先创建UIScrollView,
UIScrollView *scrollView = [[UIScrollView alloc]initWithFrame:self.view.bounds];
[self.view addSubview:scrollView];
2, 创建bgView
UIView *bgView = [[UIView alloc]init];
[scrollView addSubview:bgView];
这个view是用来放置子控件的
3, 创建子控件, 添加到bgView上面
UILabel *label = [[UILabel alloc]init];
label.text = @"标题";
[bgView addSubview:label];

UIView *headView = [[UIView alloc]init];
headView.backgroundColor = [UIColor greenColor];
[bgView addSubview:headView];

UIView *bottomView = [[UIView alloc]init];
bottomView.backgroundColor = [UIColor redColor];
[bgView addSubview:bottomView];

UIView *view1 = [[UIView alloc]init];
view1.backgroundColor = [UIColor blueColor];
[bgView addSubview:view1];

4,设置bgView的约束
[bgView mas_makeConstraints:^(MASConstraintMaker *make) {
make.edges.equalTo(scrollView);
make.width.equalTo(scrollView);
}];
[headView mas_makeConstraints:^(MASConstraintMaker *make) {
make.left.right.equalTo(label);
make.top.equalTo(label.mas_bottom).offset(20);
make.height.mas_equalTo(80);
}];
[bottomView mas_makeConstraints:^(MASConstraintMaker *make) {
make.left.right.equalTo(headView);
make.top.equalTo(headView.mas_bottom).offset(20);
make.height.mas_equalTo(900);
}];
[view1 mas_makeConstraints:^(MASConstraintMaker *make) {
make.left.right.equalTo(bgView);
make.top.equalTo(bottomView.mas_bottom).offset(30);
make.height.mas_equalTo(80);
make.bottom.equalTo(bgView);
}];